(a) Field of the Invention
The present invention relates to heat sink modules and more particularly to such a heat sink module which has the ribs of the metal base member stamped after insertion of Z-shaped foot portions of the radiation fins into respective stepped channels of the metal base member, assuring engagement tightness.
(b) Description of the Prior Art
Many conventional heat sinks have channels located on the bottom wall of a metal base member for the mounting of radiation fins. A similar design is disclosed in U.S. Pat. No. 6,571,859 in which plate-like cooling ribs projecting from a base plate at intervals and approximately parallel to each other, protrude with a connection strip into the base plate in which they are cast. U.S. Pat. No. 5,014,776 discloses a heat emitting unit in which a number of parallel, flat ribs are attached to at least one side of the main body and projecting from the main body. The ribs are pressed into place through deformation of the intermediary ridges after the ribs are inserted into channels on the main body.
Employing a soldering technique to bond radiation fins to a base member with a solder paste is not environmentally friendly. Further, the aforesaid prior art design simply has the parallel, flat ribs pressed into place through deformation of the intermediary ridges after the ribs are inserted into channels on the main body. This method simply provides a two-point clamping force to secure each flat rib to the associated channel. If the parallel, flat ribs are not accurately inserted into the channels or a vibration occurs when the parallel, flat ribs are pressed into place through deformation of the intermediary ridges after insertion into the channels, the flat ribs may not be all kept in close contact with the bottom edges of the channels to have an equal height. If the flat ribs do not have an equal height after installation, the heat emitting unit will be regarded as a defective product, and the flat ribs may vibrate or come loose from the main body.
U.S. patent application Ser. No. 12/480,461, filed by the present inventor on Jun. 8, 2009 (with priority date Apr. 17, 2009) discloses a heat sink design in which the metal base member has parallel channels located on the top wall, first ribs protruding from the top wall and respectively extending along one side of each channel and second ribs protruding from the top wall and respectively extending along the other side of each channel, and radiation fins respectively mounted in the channels of the metal base member and supported on the second ribs vertically; each radiation fin has an angled foot portion, which is inserted into one channel and secured thereto by the associated first rib upon deformation of the associated first rib by an external force. However, the channels of this prior art design are plain channels, and the insertion depth of the angled foot portions of the radiation fins is limited. In consequence, the contact area between the angled foot portions of the radiation fins and the metal base panel is limited. Further, because the first ribs simply give a downward pressure to the angled foot portions of the radiation fins when deformed, the engagement between the deformed first ribs and the angled foot portions of the radiation fins may not be tight enough. Therefore, improvement in these regards is necessary.